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3.20. Comprehensive evaluation of dynamic scintigraphy of the
esophagus and stomach

Dynamic scintigraphy of the esophagus and stomach is used for qualitative and quantitative assessment of esophageal patency and motility during swallowing, diagnosis of gastro-oesophageal reflux and for assessment of gastric motility and evacuation rate .

A comprehensive mathematical evaluation of this dynamic study includes the following main points:

Radio indicator application and study storage

The examination is usually performed lying down *) in the front projection, the scintillation camera detector is focused so that the stomach area is in the lower third of the visual field and the upper part of the esophagus just below the upper edge of the visual field.
*) For some purposes (eg in achalasia) it is appropriate to perform this examination sitting in the same projection (ie with a vertically rotated camera), so that we can assess the effect of gravity on the dynamics of the passage through the esophagus.

Approximately 50 MBq of 99m Tc-colloid mixed with a suitable beverage (fruit juice, milk, etc.) with a volume of approx. 10 ml is used as a radio indicator . Immediately after starting the dynamic scintigraphy, the patient drinks this radio indicator under the camera and immediately drinks about 100-200 ml. of an inactive beverage for the purpose of rinsing radioactive material. from the mouth and esophagus.

Recommended storage mode:

64 x 64 matrix , 16 bit,

Group 1: 120 frames after 0.5 sec. - captures the passage through the esophagus

Group 2: 60 shots after 30 sec. - captures the evacuation of the stomach and possibly late or active reflux during compression

For a more detailed capture of some fast processes of passage through the esophagus (eg in antiperistaltics), the first group of sensing can be accelerated - eg 0.2 sec./frame or shorter times and increase the number of frames accordingly so that about 40-60 sec. The examination is usually performed on an empty stomach , but can also be supplemented by repeated examinations after a meal . During the acquisition of the 2nd group, we can perform once or repeatedly a suitable compression of the stomach to provoke or. active gastroesophageal reflux - regurgitation from the stomach to the esophagus due to increased intra-abdominal pressure.

If we are only concerned with the examination of the passage through the esophagus during the swallowing of the act, it is enough to save only the first fast group. We save the entire dynamic study according to the above preselection (ie approx. 30 minutes) when we also determine the evacuation of the stomach or perform compression manipulations to detect reflux. To assess active at reflux com p resi stomach may acquire the second groups terminate in about two minutes after the last compression handling. If we only investigate the evacuation of the stomach , we usually use a solid diet , we do not investigate the swallowing act and we save only the second (slower) group (which we extend to 60 minutes); the OESOGAST program recognizes that the swallowing act is missing and evaluates only the evacuation of the stomach.

If aspiration into the lungs is suspected (due to reflux), we also accumulate:

Static scintigrams for approx. 60, 120, or 240 min. : 5 - 10 min./image,
(lung area in AP and PA projection)

In these late images (due to the already low activity in the stomach) or. deposition of the radioindicator in the lungs is clearly visible (however, it is recommended to cover the stomach and intestinal tract with a thin lead sheet).

Study evaluation

After invoking all parts of the scintigraphic study (fast group of esophageal passage, slower group capturing the regurgitation and evacuation of the stomach, or late static images) in the basic OSTNUCLINE system, we start a comprehensive program OESOGASTR - a dynamic study of the stomach and stomach .

Visual evaluation of sequential images

First, a series of appropriately absorbed images (together with the values ??of the respective time intervals) is created on the screen, capturing the passage of the radioindicator through the esophagus, then the distribution and accumulation of the radioindicator in the stomach and then its gradual evacuation to the intestinal tract (Fig.3.20.1). If still images of late phases (capturing possible aspiration of the radio indicator) have also been loaded and preselected before starting the program, the image of the sheep will be displayed at the bottom .

Based on these images, a preliminary visual assessment of this dynamic process can be made . Under normal circumstances, a swallowed bite is rapidly transported to the stomach with the help of esophageal peristalsis, so that the passage of the radioindicator through the esophagus must be sufficiently rapid and smooth , without temporary or permanent retention.

In various pathological conditions, such as achalasia, disorders of patency (narrowing of the lumen of the esophagus - tumor, external oppression of the esophagus, etc.), or a disorder of innervation of the esophagus, the passage through the esophagus slows down . In scintigraphic images, we then see a slow or uneven passage through the esophagus, which may be accompanied by retention of the radioindicator in some parts of the esophagus. However, only more pronounced abnormalities are seen in the scintigraphic images ; more detailed and sensitive analysis of the passage through the esophagus is performed in the further course of the program on curves from individual parts of the esophagus and on special mathematical constructions - transport function and condensed image.

Gastroesophageal reflux is a common pathology , when due to insufficiency of the lower esophageal sphincter,  part of the gastric contents return to the esophagus, ie an abnormally oriented movement against the physiological direction of food passage. At appropriate scintigraphic images thus formed regurgitation manifests ja ko presence of radioactive deposit mainly in the lower third of the esophagus (reflux can extend to the upper tiers of the esophagus - more and more sensitive analysis of the presence and location of reflux in the course of the program performed on the curves of slabs in Difloxacin parts of the esophagus). Reflux can occur either passively(spontaneously, under native conditions), or it can be caused by increased pressure in the stomach (appropriate compression of the stomach area) - then it is active reflux.

According to the displayed images, it is therefore possible to choose a preliminary s hunting evaluation , either an implicit standard formulation of a normal evaluation , e.g.

After oral administration of the radioindicator, we observe a
fast and smooth passage through the esophagus on scintigraphic images .
In the next course, the radioindicator collects in the stomach, from where it is
then evacuated quickly enough through the duodenum to the intest. tract.
We do not observe gastro-oesophageal reflux passive or active in
gastric compression.

Conclusion:
Visual evaluation of sequential scintigrams as well as quantitative analysis of
radiolabel passage curves indicate good patency and normal
esophageal motility, without gastro-oesophageal reflux.
The stomach has a good evacuation function.

Signature: MUDr. ,

or non-standard text. A series of images together with a verbal evaluation can be printed for documentation in pathological cases, but in normal cases this is not necessary, as significant images are included in the resulting protocol.

Designation of areas of interest and creation of curves

For a quantitative analysis of the dynamics of the esophageal passage and gastric evacuation, we mark the following areas of interest:

Esophagus - upper part ............ ROI 1
Esophagus - middle part ........... ROI 2
Esophagus - lower part ........... ... ROI 3
Stomach ........................... ROI 4

Optional:
Intest. tract .............................. ROI 5

For the ROI 1 region of interest of the upper third of the esophagus, we will use the images immediately after the arrival of the activity. To mark additional ROIs (2 - 5), move the images in the study using the arrows or the cursor below the image. If we want to monitor the evacuation of the stomach through the duodenum to the intestinal tract, we can finally mark the ROI 5 intest. tract.

The program creates curves of the time course of radioactivity from the marked areas of interest and makes appropriate corrections ……… ..
Mathematical processing of the curves follows . In all the above stages of processing, the program first asks if we want to perform them and they are executed only if the answer is positive. This saves evaluation time in cases where we are only interested in some parameters, or only visual and qualitative data.

Ana lysis of esophageal
If the recorded images capturing fast Grupa swallowing stage can (optionally) to analyze the passage of tracer esophagus. The passage curves of the radio, upper, middle and lower esophagus are displayed. In the physiological course of the swallowing act, the individual curves are single- peaked and without irregularities, the maximum of individual curves is reached gradually above the respective levels in the craniocaudal direction - first in the upper, then middle and finally lower floor, in the time range of about 2-8 seconds.

For quantification, we first set the scale of the display in the horizontal (time) direction for optimal presentation of the dynamics of the esophageal passage. The program sets this scale automatically and the operator has the option to use the " expansion " - " compression " commands to expand or contract the curves so that the details of the passage of the radio indicator through the esophagus are optimally displayed. At this scale, the esophageal curves, transport functions and condensed image will be displayed and analyzed.
On the curves of these three parts of the esophagus, the points of arrival of the radio indicator, the apex of the passage and the end of the peak are automatically marked (with the possibility of manual correction). The transit times of the radio-indicator passage are determined for each section of the esophagus[sec.].
The curves of passage through individual sections of the esophagus together with the calculated transit times including the transit (swallowing) time through the whole esophagus are displayed (Fig.3.20.2) and can be printed graphically (however, we do not normally perform this printing, curves and parameters are included in the final report). Any slowdowns and other disorders of the esophageal passage are very clearly visible on these curves ; tr anzitní times different parts of the esophagus physiological situation would not be longer than about 5-8 sec., the entire esophagus, then max. 12 sec.

Analysis of gastro-oesophageal reflux
To assess gastro-oesophageal reflux, the entire curves of all three parts of the esophagus are displayed, and we can enter the gastric compression time at the request of the program . This time point of compression is then indicated in the graph of the curves by a distinctive vertical line. Under normal conditions, after passing the radioindicator through the esophagus, all three curves of the esophagus drop to virtually zero. Gastro-oesophageal reflux is manifested on esophageal curves by retention, local peaks or oscillations of increased radioactivity ; depending on the height of the peak and whether this increase affects only the curve of the lower part, or even the curve of the middle or even the upper third of the esophagus, we can assess the significance and extent of reflux. The intensity of reflux can be (optional)quantify as a percentage. In the section after the swallowing phase, the maximum point corresponding to reflux is automatically defined (with the possibility of manual modification) on the esophageal curve. The ratio of the maximum activity in the esophagus and the corresponding activity in the stomach determines the reflux value in [ % ] for individual sections of the esophagus and the total value for the whole esophagus. According to the correlation with the moment of gastric compression, we can infer the passive or active nature of reflux.
Based on this visual and quantitative analysis, we can verbally assess the presence, significance, extent and nature of possible reflux in the box below (Fig. 3.20.3).

Analysis of gastric evacuation
After passing through the esophagus, the radioindicator is deposited in the stomach, from where, together with other gastric contents, it gradually leaves through the duodenum to the intestinal tract. The curve from the stomach area rises sharply at the time the passage through the esophagus ends, maintains its maximum value for some time and then slowly decreases due to the evacuation of the stomach. The speed of the t of a decrease indicates the speed of gastric emptying. On the stomach curve (generated from ROI4), the point of maximum and the start and end point of the drop section are automatically defined (with the possibility of manual modification) for quantification of evacuation. In this section the method of least squares diameter of beds exponential function, and draws the graph fitace. The maximum time and half-life of the evacuation of the radiondictor from the stomach are calculated [ min. ] . If the ROI5 of the intest tract has been marked, we can (optionally) supplement the analysis of gastric evacuation by quantifying the rate (gradient) of the increase in the concentration of the radiolabel in the intest. tract. The steepest part of the curve from the intest. Tract is interpolated by the least squares method and the time of arrival of the radioindicator and the maximum gradient of the increase in the concentration of the radioindicator in the intest. Tract expressed in% gastric activity per hour are determined.
Note: The half-life of the stomach for the liquid radiolabel is quite short and is not representative of the actual rate of evacuation. It is therefore more appropriate and "physiological" to use a bite of a solid diet for an objective assessment of gastric evacuation(eg rice). Such scintigraphy of gastric evacuation is then performed separately (without swallowing) and from the Oesogast program only the last part analyzing gastric evacuation is used (the program recognizes itself).

Transport function and condensed image Transport function and condensed image may be useful for more detailed analysis of esophageal passage dynamics and more sensitive detection of antiperistalsis or early gastro-oesophageal reflux .

By transport function we mean the trajectory curve of a swallowed radio indicator moving in the field of view of the camera, where on the horizontal axis is the time [ sec. ] and on the vertical axis is the distance of the center of gravity of the immediate distribution of the radio indicator at this time from the center of the stomach (Fig.3.20.4). The transport function is thus expressed as a graph of the distance of the instantaneous position of the bite from the stomach during the passage through the esophagus during the swallowing act. Under physiological conditions the transport function of the maximum initial value (in the time and at the C -throw radiotracer into the upper esophagus farthest from the stomach) during passage through the esophagus quickly and fluentlydrops to zero - in about 15-20 sec. reaches virtually all of the gastric radiolabel. With a slow passage through the esophagus (eg due to stricture of the esophagus, impaired motility or external compression of the esophagus), the decrease of the transport curve is significantly slower or uneven. Uneven movement, including oscillations, will also help us detect gastro-oesophageal reflux. Transport function evaluated in confrontation with the curves P and soot esophagus.

The condensed image is created by summing all columns of the image for each i-th frame of the dynamic study and storing the resulting summary ("condensed") column in the i-th column of the new image - the condensed image. In this image, the individual summing columns are arranged sequentially side by side , so that the i-th column of the study corresponds to the i-th column of the condensed image matrix. The trace of motion and time changes of the radio indicator distribution during the entire dynamic study (or a selected section of the dynamic study - see the following paragraph) is thus graphically concentrated (condensed) into a single image .

Fig.3.20.5. Intermediate results of transit analysis of swallowed radioindicator by comparison of esophageal curves with condensed image. Significant anomalies of the passage of the swallowed radioindicator (antiperistaltics - gastro-esophageal reflux to the middle floor of the esophagus lasting about 20 sec.) Can be clearly seen in the condensed image.

The condensed image is further mathematically transformed (normalized) so that the length of the esophageal passage is stretched to the entire vertical dimension of the image and the horizontal dimension of the condensed image corresponds to the time scale of the esophageal passage curves (set at the beginning of esophageal curve processing). A fused image is then similar transport function in the sense that the horizontal axis is also a time (derived from the serial No. s sel shots) and the vertical axis is the vertical distance from the center of the stomach. Instead of a curve, however, a clear band is shown here following the track of a radio indicator moving downwards in the field of view of the camera, or more split bands in case of some anomalies of the esophageal passage (Fig.3.20.5). The condensed image is programmed horizontallytimeline and is evaluated in confrontation with the esophageal passage curves displayed on the same time scale.

All anomalies in the movement of the swallowed radio indicator can be seen very clearly in the condensed image and the transport function (see the pathological case in Fig. 3.20.7).

Evaluation of significant images
Based on the analysis of sections of curves in the quantification of esophageal passage and half-life of gastric evacuation, the relevant images are absorbed to create images of individual phases of radiotracer passage through the esophagus (upper, middle and lower) and stomach. editing the text of the visual evaluation of these images. If you have saved up before starting the preselected y and still images late stages you will also be displayed for visual assessment if necessary. pulmonary aspiration of a radioindicator.

Final protocol
Finally, a summary structure is displayed on the screen containing images of significant phases of the dynamic study (images of radiolabel passage through individual parts of the esophagus and gastric passage), curves of radiolabel passage through upper, middle and lower esophagus, stomach and intestinal tract, transport function and condensed image . Below them is an overview of the most important quantitative parameters of passage through the esophagus and stomach calculated by the program . At the bottom of the screen is the text of the verbal evaluationwhich can be modified and supplemented. The same applies to the text of the "Conclusion" if its standard wording has been generated; otherwise we will insert the text of the final evaluation here, including the doctor's signature. Finally, a final report is printed (in the required number of copies) containing significant images, curves, calculated parameters and verbal evaluation, including the conclusion and signature of the doctor (Fig.3.20.6 - normal case, Fig.3.20.7 - pathological case).

Structure of the OESOGAST
program The OESOGAST program consists of the following parts:

OESOGAS 1 - display of a series of images, verbal evaluation,
plotting ROI, creation of curves OESOGAS 2 - mathematical processing of curves, quantification of gastric evacuation
OESOGAS 3 - construction of transport function and condensed image
OESOGAS 4 - summation of images of significant passage phases, verbal evaluation
OESOGAS 6 - display of results , text editing, report printing

At the same time, this structure shows how to proceed when the calculation is interrupted or when the program is restarted in order to repeat a certain part of the calculations. E.g. to change the texts of the verbal evaluation, just run OESOGAS4, to repeat the calculation of the parameters of the esophageal passage and gastric evacuation, start OESOGAS2.

Occupancy of SAVE AREA after the end of the OESOGAST program:
SA 1,2,3 - ROI, curves
SA 8 - transport function SA 9 - condensed image
SA 10 - image of the passage through the upper part of the esophagus
SA 11 - image of the passage through the middle part of the esophagus
SA 12 - image of the passage through the lower part of the esophagus
SA 13 - image of the passage through the stomach

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